Arc-light electrode and method of making the same.



J. T. H. DEMPSTER.

ARC LIGHT ELECTRODE AND METHGD OF MAKING THE SAME.

APPLICATION IILBI MAR.26, 1903.

1,041,752. v Patented o@1;.22,1912.

Fig. 2.

f/LL/NG ca/vrq/m/va 5 IRON OXIDE A/VU HELL OF METAL A TITAN/UM COMP- -0u/vo Witnesses Inventor.

a z John Dempster.

JOHN T. n.

"UNI-TED STATES PATENT F j n imrsrnlelor SCHENEGTADY, NEW YORK, ASSIGNOR To GENERAL nnncrmc comm, A conrona'rron or new vonx.

' ARC-LIGHT ELECTRODE METHOD OF MAKING THE SAIVIE.

Specification of Letters Patent.

Application filed March 26, 1903. Serial No. 149,641.

. Electrodes and Methods of Making the Same, of which the following is a specification.

The object of my invention is theproduction of an electrode for use in arc li hts which possesses good light-giving qualities and a good mechanical construction.

iron. In preparing the core for these elec-.

More particularly my invention relates to electrodes giving a luminous arc, that is, electrodes in which a large proportion at least of the light radiation is from the arc itself.

In the preferred form of my invention an iron tube or shell has forced into it a core formed principally of an oxid or oxids .of

trodes I employ a mixture containing about eighty per cent. of magnetic oxid 1e 0,;

about eighteen per cent. of the red oxid of.

iron Fe,O and about two per cent.'o-f some substance or substances which will lower the melting point of the mixture. The substances which I have found most advan tageous for this purpose are potassium titanate K.,TiO and potassium hydrate KOI-I. These materials are powdered and worked together dry to form an intimate mixture. The mixture is then moistened sufliciently to render it plastic so thatitcan be molded. Preferably to the water with which the powder. ismoistened I add about five per cent. of some fluid which does not evaporate so readily as water. The fluid which I ordinarily employ for thispurpose is glycerin. The plastic material is then molded into a. pencil. Any suitablejmethod' may be employed inmolding these pencils.

The method which I ordinarily employ is .that which is called squirting in which the plastic material is forced through a tubular die by hydraulic pressure. After molding the pencils they are dried in air for a suitable period which may be about twenty-four hours. They are then baked in air for another period of. about twenty-four hours, being raduallybrought up to a temperature of a out 200 C(at the end of that time; This effectually drives off the water and glycerin; The glycerin which is added cause them to flow together.

to the fluid with which the material is mois- Patented Oct. 22,1912.

ten'ed tends to hold the mass together until the material is set and prevents the crumbling which is otherwise apt to occur in a comparatively short time after the electrode begins to dry. After the baking hereinbefore described, the pencils are packed in crucibles, being surrounded with granular material such as magnesium oxid, flint, or red oxid of iron. The crucibles are then placed in a mutlie furnace which is gradually brought up to a'temperature of about 1200 C. This temperature is maintained for a period of about an hour, after which the crucible is gradually cooled oif. The

"effect of this last heating is to convert the red oxid of iron, which is unstable at the temperature employed, into the magnetic Oxid of iron, the excess of oxygen being freed and ,driven off. The packing which surrounds the electrodes in this heating action prevents any other reducing action than that named from taking place It also prevents any sagging or other distortion in the shape of the pencilsfrom taking place. The pencils when, cooled are found to be quite strong and hard and contain but very small quantities of air. Owing to their granular nature however they are but poor conductors, as the temperature -to which they have been subjected is insufficient to The red oxid of iron is added to the magnetic oxid owing to the factthat the combined mixture is more easily molded into a homogeneous mass than is the magnetic oxid when used alone. After the pencils cool down they may be rubbed slightly with emery paper or the like if necessary to smooth them, and are then forced into thin tubes or shells of iron. One end of the tube thus formedis treated to make it conductive. A simple muflie furnace in which the electrodesare tion in the tube. If the temperature of the treated be raised somewhat above1200 (l,

the granular material composing the pencils will flow together sufficiently to make the pencils comparatively good conductors of electricity. When so treated, the pencils may be used as electrodes without incasing them in the iron tube. Unless, however, a considerable amount of care is exercised in preparing the electrodes in this manner, they are liable to be defective by reason of the blisters andother distortions in their shape produced in heating them to such a temperature.

In the accompanying drawings Figure 1 is an elevation showing the completed electrode; Fig. 2 is an end view showing the fused end; Fig. 3 is a sectional elevation of the completed electrode; and Fig. 4 is an elevation showing the pencil before insertion in the tube. 1

Referring to the drawings, 1 represents a shell or tube of sheet metal which may be formed out of a strip the parallellong edges of which may be united in any suitable manner at 2 as by a tinners seam. The pencil formed in the manner hereinbefore de= scribed shown at-3 is forced into this tube, the parts being so proportioned that atight fit is obtained. In practice the iron tube may be somewhat longer than the penciLas shown in Fig. 3, there being no necessity for filling with the pencil that part of the tube which is held in the current-carrying clamp or holder, as it is ordinarily thrown away when the electrode is consumed to that point. The pencil may be cored as indicated at 4, although ordinarily I do not prefer this construction. The end of the electrode after fusing has the appearance indicated at 5. If the fused end of the electrode should be knocked ofl" or otherwise removed, the electrode would not be seriously damaged as there is no liability of the pencil escaping from the tube and the end of the electrode can be readily fused over again.

In operation the metallic iron forming the shell fuses together with the iron oxids forming the pencil, and the material thus fused slowly vaporizes, giving a highly luminous arc. The otassium titanate or hydrate or other sim' ar substance which is mixed with the other ingredients of the pencil reduces the fusing and vaporizing points somewhat, and thereby increases the material which is vaporized upon the passage of a given current. This tends to increase the volume of the arc and to steady the arc in operation.

What I' claim as new and desire to secure by Letters Patent of the United States, is,-

' 1. The method of facilitatingthe-shaping of electrodw composed principally of magnetic oxid of iron, which consists in add' a comparatively small portion o f red oxi of iron to the magnetic oxid of'i'ron prior to the shaping;

, 2. The method of facilitating the shaping of electrodes composed principally of the magnetic oxid of iron, which consists in adding red oxid of iron and a suitable binding material to the magnetic oxid of iron I prior to the shaping of the electrode.

3. The method of treating electrodes consisting mainly of iron and oxygen chemically combined, which consists in placing them in a granular mass of non-reducing material and then baking them,

4. The method which consists in forming 5 a mixture composed principally of iron and oxygen chemically combined, molding into pencils, forcing the pencils into iron shells, and then treating the' arcing end of the inclosed pencil to increase its conductivity. so

5. The method of producing a pencil composed principally ofmagnetite, which consists in mixing together magnetite with a red oxid of iron, treating the mixture to make it plastic, molding the plastic material into pencils, and then converting the red oxid of iron into magnetite.

6. The method which consists'in forming electrode pencils from a mixture containing magnetic oxid of iron and red oxid ofiron, so and then converting the red oxid of iron into the magnetic oxid of iron.

7. The method which consists in forming electrode pencils from a'mixture containing two oxids of iron, then heating the mixture to convert it into one oxid of iron.

8. The method which consists of forming a mixture of red oxid of iron and the magnetic oxid of iron, moisteningthe mixture to render it plastic, molding he plastic material into pencils, and heating the pencils to convert the red oxid of iron contained therein into the magnetic oxid of iron.

' 9. The method which consists in forming a mixture containing red oxid of iron with magnetic oxid of iron, moistening the mix-.

- ture to render it plastic, molding the plastic material into pencils, heating the pencils to convert the red oxid contained therein into the magnetic oxid of iron, and then inserting the pencil into an iron tube.

10. The method which consists'in formin a mixture containing red oxid of iron an the magnetic oxid of iron, moistening the mixture to render it plastic, molding the plastic material into pencils, heating to convert the red oxid contained therein into the magnetic oxid of iron, inserting the pencils-into an iron tube or shell, and then fusing gether.

11. An are light electrode consisting of an iron tube or shell filled with a pencil composed principally of iron and oxygen chemically combined, one end of the pencil and 125 the tube being fused together to increase the conductivity of said end. 12. An are light electrode composed principally of iron and oxygen chemically com- 'bined and a small quantity of some other 13fl one end of the tube and pencil to- 15 '16. An are light electrode composed principally of iron oxid, but containing a substance which melts at a lower temperature than said oxid.

17 An are light electrode metallic in composition, andcontaining a titanium salt.

18. An are light electrode metallic in composition, and containing a salt which comprises both potassium and titanium.

In witness whereof, I have hereunto set my hand this 25th day of March, 1903.

I JOHN T. H. DEMPSTER. -Witnsses:

BENJAMIN B. HULL, HELEN Ouronn. 

